The present invention relates to an underrun protection arrangement for a vehicle having a frame, comprising an impact element arranged in a position that corresponds to an anticipated impact from a force in the event of a collision with another vehicle, and at least one energy-absorbing connecting element which connects the impact element to the frame and which is designed to be compressed in the event of said collision.
Larger motor vehicles, such as load-carrying commercial vehicles, are nowadays designed with relatively high ground clearance. One major reason for this is the need to be able to use the vehicle when driving on uneven ground, for example. Today's commercial vehicles normally have a ground clearance which at the front of the vehicle is in the order of 400 mm.
However, the fact that a commercial vehicle normally has a relatively high ground clearance constitutes a serious road safety risk. This is due to the fact that in any head-on collision between the commercial vehicle and a passenger car, there is a risk that the front section of the passenger car will penetrate under the front of the commercial vehicle and thus become wedged between the roadway and the front underside of the commercial vehicle. This can lead to the front of the commercial vehicle penetrating the passenger compartment of the passenger car with enormous force, which in turn may result in serious injuries to the occupants of the vehicle. In unfortunate cases, the commercial vehicle may even continue forwards and roll over the passenger car, which can obviously result in even more serious injuries.
Various solutions have been proposed for solving the above-mentioned problem. One solution is to provide the load-carrying commercial vehicle with a special underrun protection arrangement in the form of a reinforced structure, such as a force-absorbing beam element, which is arranged horizontally at the front of the commercial vehicle. More specifically, this beam element is arranged in a position that corresponds to a point of impact from an anticipated force in the event of a collision with a passenger car. By means of such an element, it is possible to prevent a passenger car penetrating under the front of the commercial vehicle in the event of a collision.
Furthermore, such an underrun protection arrangement can be arranged so as to absorb energy in the event of a force acting upon it during a collision. This further reduces the risk of serious injuries in the event of a collision.
It is previously known from the patent document U.S. Pat. No. 3,981,114 to use an energy-absorbing device in the form of a column arrangement to be used as an energy-absorbing device in an automobile bumper. To this end, the arrangement comprises two column elements in the form of a first column element which is arranged in a telescopic manner inside a second column element. Upon impact during a collision, the second column element will initially be collapsed. In a second phase during the collision, the second column element will be collapsed together with the first column element. As a result, a controlled collapse sequence can be obtained.
It can be noted that the previously known devices of the above-mentioned type are not arranged for providing a highly controlled energy absorption in an underrun protection arrangement. Such demands are in particular relevant in those cases which involve a passenger car colliding with a load-carrying commercial vehicle, where certain requirements exist regarding, for example, the energy absorption and deformation length of the underrun protection.
It is desirable to provide an improved energy-absorbing underrun protection arrangement for a load-carrying commercial vehicle, which in particular provides a highly controlled energy absorption under impact stress during a collision with a conventional car.
An arrangement of the above-mentioned type according to an aspect of the present invention is provided, wherein said connecting element comprises an outer section and an inner section which are telescopically arranged so that displacement of the outer section in relation to the inner section may occur upon said impact while energy is absorbed, said connecting element also comprising an energy-absorbing unit arranged to be compressed while absorbing energy during said displacement.
By means of an aspect of the invention, certain advantages can be obtained. For example, a force generated by an impact during a collision can be absorbed with a minimum risk of injury of the occupants of the passenger car, who are the ones most at risk of injury in the event of a collision between the passenger car and the commercial vehicle.
Furthermore, an aspect of the invention provides a high degree of controlled energy-absorption as a result of the above-mentioned telescopically arranged connecting element. In accordance with the invention, the energy absorption may take place during a relatively long telescopic displacement of the connecting element. Also, the invention may be arranged so that the connecting element is not telescopically displaced until the force acting on the impact element exceeds a predetermined threshold value. The controlled energy-absorption can thus be optimally adapted to the impact stress during an anticipated crash situation between a passenger car and a commercial vehicle.
It is also desirable to provide an improved energy-absorbing underrun protection which is adapted to offset collisions (i.e. in relation to the direction of travel of the vehicle). According to an aspect of the present invention, particular coupling elements can be provided which allow the connecting elements to pivot with respect to the impact element and the vehicle frame.